1. Field of the Invention
This invention relates to freed-fiber spinning devices of the type comprising a hollow rotor which rotates at high speed, the yarn being delivered in the geometrical axis of said rotor, and a false-twist rib placed within an elbowed portion of an exit tube of the rotor. The elbowed portion of the exit tube is subjected to the partial vacuum which prevails within the rotor and has a direction such that the path of the textile yarn is modified as it passes against the above-mentioned rib under the action of takeup means and that the rib extends across the geometrical plane formed by the two lengths of yarn upstream and downstream of said rib.
In more precise terms, the invention relates to the structure of the elbowed exit tube of the rotor and to the design of the false-twist rib placed within said exit tube.
2. Description of the Prior Art
As already disclosed, for example, in British Patent Specification No. 2017167 published Oct. 3, 1979, assigned to the same assignee of this application, and French patent No. 2,210,684 dated July 12, 1974 similarly assigned, it is known to design the false-twist rib in the form of a portion of a turn of wire which is wound in a helix and forcibly inserted in the elbowed tube. While this structure proves satisfactory insofar as it achieves the desired result, namely a temporary increase in twist of the textile yarn for improving the spinning process, it is open to criticism on the ground of excessively rapid wear of the turn of wire against which the textile yarn is continuously applied in rubbing contact at high speed. Furthermore, the replacement of a worn helical wire by a new wire element is not a convenient operation.